324 Intelligence and Miscellaneous Articles, 



nin may absorb an atom of water, there would result gallic and acetic 

 acid. In fact, O H'6 12 + 0H°- = 2 (C H 6 O) + C 4 H 6 s re- 

 presents 2 atoms of gallic acid and 1 atom of acetic acid. — Journal 

 de Chimie Medicate, Mai 1837. 



SPONTANEOUS COMBUSTION OF LINSEED OIL AFTER ITS BE- 

 COMING DRY. 



The heating of linseed oil when soaking into soft vegetable fibrous 

 or porous matters, has been several times brought into public no- 

 tice ; but we have not observed this effect when the oil has become 

 dry and hard. 



A manufacturer at Plymouth had occasion, two or three years 

 since, to grind some red lead in oil, and a cask of it was set aside 

 till it had become hard, and consequently useless, which soon hap- 

 pens to that mixture, red lead being a rapid " dryer." Some months 

 since, being annoyed at this cask lying about the warehouse, he 

 ordered it to be knocked to pieces and the contents powdered, to 

 see if anything could be made of it. This being done in the even- 

 ing, and the powder put into a box, he was surprised in the morning 

 by a smell of fire, and after searching the warehouse over, perceived 

 smoke issuing from this box ; water was thrown in, and when all 

 was cold the contents were turned out. The bottom of the box was 

 found charred, the matter next it brown and partly reduced, and so 

 to about the centre of the mass, from whence it shaded off through 

 chocolate colour to the surface, which retained its redness, but was 

 clotted hard together like all the rest. 



The same manufacturer has occasion for large quantities of oiled 

 paper, which when quite dry and no longer adhesive to the touch, 

 he has sometimes put together in piles, but has been obliged to se- 

 parate them again on account of the heat generated, which has been 

 such as to threaten ignition. 



August 5, 1837. 



PROCESS FOR INK DEVOID OF FREE ACID. BY R. HARE, M.D. 



PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF PENNSYLVANIA.* 



Writing ink is usually constituted of the tanno-gallate of iron and 

 a portion of sulphuric acid, which had existed in the copperas or sul- 

 phate of iron employed as one of its ingredients, the tanno-gallate 

 being suspended and the acid dissolved in the water. This free acid 

 is injurious to iron pens. Dr. Hare has observed that when an in- 

 fusion of galls is kept over finery cinder till saturated, it forms a 

 beautiful ink, in which of course there is no free acid. 



This ink is rather more prone to precipitate than that made with 

 sulphate of iron, and this propensity is not counteracted by the ad- 

 dition of gum arabic. But, on the other hand, it has the advantage 

 of being easily suspended again by agitation, not forming any con- 

 crete matter insusceptible, like common ink grounds, of that distri- 

 bution in water which is necessary to good ink The tanno-gallate 



* The above and three following notices have been communicated by the 

 author. 



